NATURE 



[June i i, 



that the exceptional appearances were most probably 

 due to the influence of the new Electric Railway, 

 three miles in length, and having terminal stations in the 

 City and at Stockwell. A comparison being made be- 

 tween the observed times of interference with the earth- 

 current registers, and the published times of running of 

 the Electric Railway trains, it was found that these were 

 simultaneous. Further, in the early part of the year, 

 during the period in which the earth-current registers 

 were free from interference on Sunday, there were 

 correspondingly no Sunday trains. But on Sunday, 

 April 5, it appears that trains commenced to run on 

 Sunday afternoon, the same day that Sunday inter- 

 ference was first noticed at Greenwich, and these Sunday 



The line of the Electric Railway runs from about 

 north-east to south-west magnetic, or more accurately 

 the azimuth of the line, reckoning from magnetic north 

 towards east, is about 50°. The nearest earth-plate to the 

 railway is the N. K.E.J, plate, which is distant from the 

 railway, in a perpendicular direction from it, about 2^ 

 miles. 



The correspondence so far as the comparison goes is 

 complete. During the periods of interference the register- 

 ing needles at the Observatory are in continual vibrati n. 

 Whether the impulses are in one direction only or in both 

 directions, and what is their frequency, cannot be readily 

 determined from the registers. Eye observation of the 

 needles may perhaps reveal something to us on these 



afternoon trains have been since continued. The whole 

 matter is better seen in the-annexed tabular statement:— 



Times of interference with 

 earth-current registers at the „ . . „, . ^ ., 



Royal Observatory, •^'^^" service on Electric Railway. 



Greenwich. 



On week days. 

 From shortly before 7 

 a.m. uriiil ihortly after 

 II p.m. 



On Sundays, commencing 

 April 5. 



From about I p.m. un- 

 til 10 p.m. or shortly 

 afterwards. 



On week days. 



First train from Stockwell 6.40 a.m. 



.. ., City ... 6.50 a.m. 



Last train from Stockwell 10.46 p.m. 



M ,, City ... 10.58 p.m. 



On Sundays, commencing April 5. 



First train from Stockwell i.o p.m. 



.. . ,, City ... 1.5 p.m. 



Last train from Stockwell 9.30 p.m. 



>» » City ... 9.30 p.m. 



points. The abnormal excursions of the needles indicate 

 a change of potential varying from a small fraction of a 

 volt to perhaps the one-third of a volt or more. When any 

 marked earth-current action arises, the interference be- 

 comes in some degree neutralized, and less marked in 

 character. 



It was found in the course of previous experiments, that 

 when, instead of employing the complete A.W.-L.W. 

 circuit, the A.W. branch only was allowed to register, by 

 putting the wire to earth at Greenwich, the amplitude of 

 vibration of the needle was not perceptibly changed, 

 neither was it changed when the L.W. branch only was 

 allowed to register. Correspondingly, when the B. branch 

 alone of the B.-N. K.E.J, circuit was allowed to register, 

 the vibration was much diminished, whilst with the 

 N. K.E.J, branch alone registering it was much increased. 



William Ellis. 



THE ANNUAL VISITA TION OF THE RO YAL 

 OBSERVATORY. 



HTHE Report presented by the Astronomer-Royal this 

 year is of more than usual interest. The first part 

 deals with proposed new buildings. 



It has been decided that the museum or storehouse for 



NO. I 128, VOL. 44] 



portable instruments and apparatus should be built so as 

 to form the central octagon of a future cruciform struc- 

 ture in the South Ground, which would accommodate the 

 physical branch of the Observatory, and would carry the 

 Lassell equatorial and dome at such a height above the 

 ground that the neighbouring trees would not interfere 

 with the effective use of the instrument. The building 



